fix main branch reference in workflow

Author: mmcgarr

.github/workflows/push.yaml

@@ -26,7 +26,7 @@ jobs:
           name: bin
           path: bin/
   docker-build-push:
-    if: github.ref_name == 'master' || startsWith(github.ref, 'refs/tags/v')
+    if: github.ref_name == 'main' || startsWith(github.ref, 'refs/tags/v')
     needs: build
     runs-on: ubuntu-latest
     steps: